This man took 40,000 ecstasy tablets in his 20s

At 37, Mr. A.'s memory loss and inability to concentrate started bothering him so much that they drove him to seek medical help. He admitted to his doctors, including Dr. Christos Kouimtsidis of the London Psychiatry Centre, that he may know the reason for his limited mental capacities: He estimated that he took about 40,000 ecstasy tablets from age 21 to 30, when he stopped using the drug.

Kouimtsidis and some of his colleagues at the University of London subsequently published a case report about Mr. A., which appeared in the journal Psychosomatics in 2006. (The full report is available online via the Beckley Foundation, a U.K. nonprofit aimed at increasing research on drugs and drug policy in that country.)

The Patient: Mr. A. used ecstasy with increasing frequency in his 20s, he told his medical team; he dabbled in other drugs, too, including marijuana and cocaine, but ecstasy was always his go-to substance. From ages 21 to 23, he only used it on the weekends, usually taking about five tabs at parties. At 23, however, he began taking MDMA every day, averaging 3.5 tablets per day over the next three years. From ages 26 to 30, his ecstasy use hit its peak, and he estimates that he was averaging 25 pills per day. He stopped at age 30, after "collapsing" at parties on three separate occasions.

The Problem: Though he hadn't taken MDMA for seven years, Mr. A. was still experiencing strange side-effects. "[H]e felt as if he was still under the influence of ecstasy and suffered several episodes of 'tunnel vision,'" Kouimtsidis writes in the case report. "He eventually developed severe panic attacks, recurrent anxiety, depression, muscle rigidity (particularly at the neck and jaw levels), functional hallucinations, and paranoid ideation." Mr. A. also had trouble with his short-term memory and concentration, such that he found it difficult to follow even a simple set of instructions; Kouimtsidis also reports that his patient showed signs of "disorientation to time," though he doesn't elaborate on what he means by that.

The Diagnosis: Mr. A.'s physicians were stumped. On the one hand, their patient showed signs of cognitive impairment; on the other, brain scans revealed no physical evidence of abnormalities or atrophy. Eventually, Mr. A. was admitted to the hospital's brain-injury unit, where the medical team helped him come up with ways to compensate for his trouble with memory and concentration.

It's entirely possible that Mr. A. might have been exaggerating or misreporting the ecstasy use of his youth — this is a man, after all, who was admittedly struggling with memory problems. (And 40,000 pills is an absurdly high number!) But his case report adds to the mixed evidence the research has turned up on the potential long-term harm from ecstasy use. One study published in 2013 in Addiction, for example, suggested that people who took ten or more pills over one year were more likely to show signs of impaired short-term memory than people who had not taken MDMA at all.

But, then again, a 2011 paper published in that same journal found "little evidence of decreased cognitive performance in ecstasy users." (Though that study didn't include anyone who'd used anywhere near as much ecstasy as Mr. A.) And the drug has therapeutic potential, too, of course: Veterans with PTSD are increasingly turning to MDMA to help ease their symptoms. Much more research is needed before scientists can say anything definitive about the long-term effects of ecstasy use, and while scientists can only learn so much from individual case reports like Mr. A.'s, every little bit of data helps to form a more complete picture.